Method for selecting map information, and navigation device

ABSTRACT

Proposed is a method and a navigation device, a method for selecting map information from a digital map on the basis of a predefined polyline being used on the digital map, and, in addition to the information defined by the polyline, the map information including further information regarding a route corridor.

BACKGROUND INFORMATION

Today's vehicle navigation systems are essentially made up of thesubsystems digital road map, computing module for calculating the route,position determination, system management, vehicle sensory system fordetecting vehicle movements, and an input unit and an output unit foroperating it and navigating. The digital road map is usually availableon a storage medium, e.g. a navigation CD-ROM, in the vehicle. After thedestination is input, the navigation system determines the route on thebasis of the available map material. The calculated route is used forthe navigation. If the driver leaves the current route during the trip,then the navigation device determines a new route on the basis of thecurrent position.

SUMMARY OF THE INVENTION

The method of the present invention and the navigation device of thepresent invention, which possess the features of the dependent claims,have the advantage over the background art, that it is only necessary toaccess the map data which are also needed during navigation, and that itis not necessary to access the entire digital road map. In addition, itis advantageous that, during the use of a digital map in the vehicle,the complete route along with a corridor and any further information ispresent in the RAM, so that during the active navigation, basic datathat are normally stored on a mass storage unit, such as a CD-ROM, donot have to be accessed. It is advantageous that, when the method of thepresent invention is used in a main station, basic data, i.e. a digitalroad map, first of all do not have to be available, e.g. on a CD-ROM, inthe navigation device bound to the vehicle, and costly components maytherefore be dispensed with, and second of all, the route corridor mayconstantly be generated in a main station from the newest mapinformation. Therefore, the reduction in the amount of data constantlyneeded in comparison with a complete road map is advantageous, when onlya corridor around a navigation route from the starting location of thenavigation to the destination of the navigation is used. This allows areduction in the costs, for example, for storage media, any transmissionof the data, e.g. via an air interface, and the user fee for the mapdata, in particular in the case of a service provider. Furthermore, thisadvantageously increases the speed of accessing the elements of theroute corridor, since the smaller amount of data allows the entirecorridor to be stored in the quicker RAM.

In addition, it is advantageous that the at least one parameter providesfor the selected map information being tolerant of one error or tolerantof two errors, and/or being tolerant of multiple errors in the startingregion and destination region of the polyline. This provides asufficient amount of information for returning to the planned route inan optimum manner, when one or two and/or, in the starting anddestination regions, several issued driving instructions are notfollowed. This does increase the amount of information regarding theroute corridor, but increases the flexibility of the information for thepurposes of navigation, which results, on the whole, in an advantage.

In addition, it is advantageous that the at least one parameter providesfor the selected map information being tolerant of one, two, or multipleerrors as a function of the class of road. In this manner, the amount ofinformation to be provided in the route corridor is not unnecessarilyincreased by a generally high error tolerance, because a larger errortolerance is set for parts of the main route shown by experience to beprone to error (e.g. a standing area or urban area), than for partsshown by experience to be less prone to error (such as freeways).

In addition, is advantageous that the at least one parameter providesfor the selected map information containing navigational instructions.Therefore, route corridors according to the present invention and mapinformation selected according to the present invention may also be usedin navigation systems, which do not determine their own route. This isrendered possible by storing the navigational instructions in thecorridor or in the selected map information. However, a routedetermination may still be carried out inside the corridor, since all ofthe relevant map data are still present.

Furthermore, it is advantageous that the navigational instructions leadback to the polyline on the shortest, quickest, or most efficient route(side route) and/or lead to the destination (alternate route). In thismanner, a more or less extensive route corridor may be generated,depending on what a user desires.

BRIEF DESCRIPTION OF THE DRAWING

An exemplary embodiment of the present invention is represented in thedrawing and explained in detail in the following description. Thefigures show:

FIG. 1 a representation of a first example of a route corridor accordingto the present invention;

FIG. 2 a representation of a second example of a route corridoraccording to the present invention;

FIG. 3 a representation of a third example of a route corridor accordingto the present invention;

FIG. 4 a representation of a fourth example of a route corridoraccording to the present invention;

FIG. 5 a representation of a fifth example of a route corridor accordingto the present invention; and

FIG. 6 a navigation device according to the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention describes a method by which a route corridor isgenerated from a known route, the route corridor having the featurethat, in addition to the actual main route that includes, inter alia,the road segments of the original map, other road segments on which thenavigation device may navigate are considered. The “width” of the routecorridor or the number of additional road elements or road segments isgenerated according to predefined parameters, such as the toleratednumber of instances of erroneous driving. Apart from the road segments,which are selected from the digital map and may be used for a routecalculation inside the corridor, navigational instructions arealternatively or additionally generated for sections of road. Dependingon the setting of the parameters for implementing the method, thepresent invention provides for these instructions to be generated, e.g.in such manner, that they either lead one back to the original mainroute on a side route leading after some time, or that they navigatealong an alternate route. In this connection, the main route, the sideroute, or the alternate route may overlap any number of times, i.e. themain route and/or one or more side routes may be included in thealternate route, and vice versa.

The navigational instructions in an alternate route may be generated insuch a manner, that the vehicle is guided on the best route to thedestination. This normally results in the navigational instructionsleading the driver back to the main route again. However, it may also beprovided and desirable, that the driver be lead on a completelydifferent, alternate route to the destination, since a completely newroute to the destination was found from this point.

Since, as a rule, the best side route after driving incorrectly is aturning maneuver back to the main route, the first part of the road maybe alternatively provided with a high driving resistance for theroute-determination algorithm while generating the route corridor.Therefore, a side route or alternate route is primarily determined,which does not lead back directly to the main route by way of a turningmaneuver.

From a known, predetermined main route or polyline, which is matched toa digital map, i.e. a digital map is fit to the route or polyline, themethod of the present invention generates a route corridor according toone or more criteria or parameters of the present invention. A possiblecriterion of the present invention is referred to as “tolerance for oneerror”. This means that the driver is always conceded exactly oneincorrect driving maneuver, if he is on the calculated route, i.e. if heis on the main route. As soon as he does not follow a navigationalinstruction, he departs from the proposed main route, but he continuesto be guided to the destination, as, after a short time, he is guidedagain to the main route via a side route, or guided on an alternateroute to the destination. In this case, a route that leads from thepoint on the main route, at which the main route was exited, to the nextconvenient point of access to the main route is designated as a sideroute. A route that specifies the best, i.e. either the shortest or thequickest or the most efficient route to the navigation destination isreferred to as an alternate route.

Therefore, the method according to the present invention first of allcalculates the route corridor from a main route, i.e. from a selectedpolyline, and secondly, from a digital map that is stored, for example,on a navigational CD-ROM. In this context, the main route is determinedby an arbitrary method, e.g. a navigation algorithm in a navigationdevice, which is installed in a vehicle or in a main station at aservice provider. In particular, the number of tolerated errors ispreselected, an expanded starting region is defined, and an expandeddestination region is defined, as parameters for controlling theimplementation of the method according to the present invention. Thisinformation is likewise made available to the method of the presentinvention. The expanded starting and destination regions are regionsaround a starting point or destination point, in which the routecorridor or the selected map information completely contains the digitalmap.

The corridor is placed about the selected route regardless of the methodused for determining a route (criteria of speed, time-efficiency, etc.).The corridor is generated in such a manner, that additional roadsegments from a map database are added to the existing roads or routeelements at the nodes (intersections). The number of road segments addedmay be specified by inputting at least one of the following parameters:Specification of the error tolerance, detail areas in the starting anddestination regions, error tolerance as a function of the class of road.Tolerant of one error means that the driver may be given a navigationalinstruction despite making a wrong turn. Tolerant of two errors means,that either the driver may make two wrong turns in direct succession andalso still be given a driving instruction, or that the driver may make awrong turn on both the main route and a side/alternate route and alsostill be given a driving instruction. In the event of another error, thevehicle may be situated outside the corridor. In this context, it isconceivable for the selected error tolerance to be a function of theunderlying class of road. Thus, a higher error tolerance may be grantedin urban areas than on freeways.

Starting or destination regions may optionally be generated as acomplete map section, since, in the starting region or destinationregion, which is normally a municipal area, the probability of not beingable to follow the instructions of the navigation device is highest. Inthe area of the starting region, a complete map section may acceleratethe initialization of a map-matching algorithm. In addition, a map isprovided in the destination region for pedestrian navigation.

Shown in FIG. 1 is a representation of a first example of a routecorridor according to the present invention. A starting point 100 and adestination point 200 are specified, as well as a starting region and adestination region, the starting region being denoted by a circleprovided with reference numeral 105, and the destination region beingspecified by a circle referred to by reference numeral 205. The route orthe predetermined polyline is represented by the bold-faced lines inFIG. 1. In FIG. 1, it is apparent that not only the bare polyline isrepresented, but also options for turning off, which are displayed aslines of normal width along the main route, i.e. along the polyline.

Shown in FIG. 2 is a representation of a second example of a routecorridor according to the present invention. Starting point 100,destination point 200, expanded starting region 105, and expandeddestination region 205 are again shown.

However, in contrast to the first example of a route corridor accordingto present invention, the route corridor in the second example includes,in addition to the turn-offs from the main route, branch loops of thedigital map connecting to the main route.

FIG. 3 shows a third exemplary embodiment of a route corridor accordingto the present invention. A first arrow points from starting point 100towards a first intermediate point 110. A second arrow points from firstintermediate point 110 to a second intermediate point 120. A third arrowpoints from second intermediate point 120 to a third intermediate point130. A third arrow points from third intermediate point 130 to a fourthintermediate point 140. A fifth arrow points from fourth intermediatepoint 140 to a fifth intermediate point 150. A sixth arrow points fromfifth intermediate point 150 to a sixth intermediate point 160. Aseventh arrow points from sixth intermediate point 160 to a seventhintermediate point 170. An eighth arrow points from seventh intermediatepoint 170 to an eighth intermediate point 180. A ninth arrow points fromeighth intermediate point 180 to destination point 200. The first,second, third, fourth, fifth, sixth, seventh, eighth, and ninth arrowsare parts of the main route, just as intermediate points 110 through180. In addition to the arrows of the main route, other arrows arerepresented in FIG. 3 by dotted lines. These belong to side routes. Inthe case of navigating a motor vehicle, for example, it may be preferredthat the vehicle remain on the main route from starting point 100 todestination point 200. If, however, this is not the case due to variousreasons, e.g. when the driver does not follow an instruction of thenavigation system, then a navigation system needs information above andbeyond the information included in the polyline. To this end, thepresent invention provides the route corridor, which includes thenecessary information. According to the present invention, the routecorridor includes variable amounts of information as a function of theparameters for implementing the method. Depending on how the parametersof the method are set, the route corridor may include a side route whichis designed to guide one on the quickest route from the point ofdeviating from the main route, back to the main route. Arrowsrepresented as dotted lines are provided in FIG. 3 for the purpose ofillustrating these circumstances. The arrows, i.e. both the arrows ofthe main route and the arrows of the side routes, correspond tonavigational instructions. Therefore, when the route corridor accordingto the third example of a route corridor is supplied to a navigationsystem not able to calculate its own route, then the navigation systemmay reach destination 200 with the aid of the navigational instructions.When the navigation system supports its own route determination, thenthe data of the route corridor are used in a known manner to determinethe most suitable route to the destination, the navigationalinstructions being generated in the course of such a routedetermination, from the information present in the route corridor. Then,navigational instructions would not be necessary (but also not ahindrance) in the route corridor as such, so that, according to thepresent invention, the arrows represented in the third example of aroute corridor are also provided as mere connecting lines without thedirection information. In this connection, is particularly useful thatthe present invention provides for the user, i.e. in particular avehicle, not being guided to the destination by a turning maneuverimmediately following the departure from the main route. Therefore, isuseful for the present invention to assign, from the point of departurefrom the main route, a high driving resistance to a number of roadsegments of the main route during the recalculation of the route, inorder to prevent the vehicle from being navigated directly to the mainroute again, i.e. using a turning maneuver. This renders an algorithmfor route determination more independent of the originally plannedcourse of the route between the starting point and the destinationpoint, i.e. more independent of the main route.

In order to generate the navigational instruction, the part of the mainroute, on which the driver would have traveled next, may alternativelybe assigned a driving resistance as well, for the determination of aside route or alternate route. Since the driver does not normally leavethe main route without a reason, an example being the departure from themain route on account of a traffic jam lying ahead, this method has theadvantage that one is not necessarily returned to the main route at thenext opportunity, but rather according to the selectedroute-determination criteria, in particular the shortest, most rapid,and most efficient trip, and that the driving resistances are weighedout. Therefore, this normally yields a side route or alternate route,which travels completely around the part of the main route blocked bythe driving resistance.

A fourth exemplary embodiment of a route corridor according to thepresent invention is represented in FIG. 4. The parts of the main routeand intermediate points 110 through 180 are again represented here. Inaddition, alternate routes are made up of arrows represented by dottedlines. The parameters for implementing the method according to thepresent invention are therefore set for generating the fourth example ofa route corridor in such a manner that, in the event of departures fromthe main route, not the side routes, but rather the alternate routes areintegrated into the route corridor. The arrows also symbolizenavigational instructions in the fourth example of the route corridoraccording to the present invention.

A fifth example of a route corridor according to the present inventionis represented in FIG. 5. In addition to the arrows of the main route(solid arrows) and the arrows of the side routes and alternate routes(dotted arrows), in each case, the first road sections branching off arealso represented in FIG. 5, using short, dotted lines ending in a point,i.e. the route corridor according to the fifth example also includesinformation about the road segments still present at an arbitrary point,which are outside the curve of the main route, the side routes, and thealternate routes. The road sections branching off allow reliabledifferentiation between the states of the driver driving correctly orincorrectly with respect to the driving instructions.

A navigation device 10 or also a navigation system 10 according to thepresent invention is represented in FIG. 6. the Navigation device 10includes a memory 20, which especially takes the form of a main memoryand is rewritable. Memory 20 is, in particular, a memory device havingrapid access. Navigation device 10 also includes a route-determinationunit 30 and a control unit 12. Using position-finding data supplied tonavigation device 10 by a position-finding unit not shown, and usingdestination information, route-determination unit 30 convertsinformation coming from a digital map into navigational instructions,which are stored, e.g. in memory 20, the storage being controlled bycontrol unit 12. Route-determination unit 30 is optionally present.

In addition, the navigation device includes a mass storage unit 50and/or an air interface 60. A digital map may be stored in the massstorage unit, in particular in the form of a CD-ROM. Information fromnavigation device 20 is transmitted and/or received via the airinterface. The received information includes, in particular, informationthat a service provider not shown transmits to the navigation device asa part of the digital map, in particular in the form of a routecorridor. The navigation system may demand map information or otherinformation from a main station, e.g. a service provider, via airinterface 60.

Main memory 20 stores data for a current navigation operation. When amass storage unit is present, a route determination is carried out onthe digital map in the mass storage unit, the digital map of massstorage unit 50 having to be accessed in response to each deviation fromthe route determination, if only the information regarding the mainroute is available. According to the present invention, the mass storageunit is accessed only once and a main route is defined. A route corridoris generated for this main route and stored in main memory 20. Access tomass storage unit 50 is then no longer necessary for the same navigationguidance.

In the case in which a mass storage unit 50 is absent, the same appliesto the communication with a main station of a service provider via airinterface 60. The inquiry including the relevant starting data anddestination data of the navigation is transmitted to the serviceprovider, and the service provider does not only transmit the main routeto the navigation unit or navigation device, but also transmits theroute corridor of the present invention, so that a new inquiry to theservice provider is not necessary in the case of a deviation from themain route provided.

In the navigation device, navigational instructions are used when it ispossible to calculate the route, or the navigational instructionspresent in the route corridor as a function of the parameter setting ofthe method according to the present invention are used in the event thatthe route-determination device is absent.

1. A method for selecting map information from a digital map,comprising: providing a predefined polyline that defines information;selecting map information that includes a route corridor as a functionof at least one parameter; and if the at least one parameter providesfor the selected map information being tolerant of an error, guiding adriver on one of a side route and an alternate route, wherein one of:the at least one parameter provides for the selected map information tobe tolerant of multiple errors in a starting region and a destinationregion of the predefined polyline, and the at least one parameterprovides for the selected map information to be tolerant of at least oneerror as a function of a class of a road.
 2. The method according toclaim 1, wherein the at least one parameter provides for the selectedmap information to include a navigational instruction.
 3. The methodaccording to claim 1, further comprising: formatting the navigationalinstruction to lead back to at least one of a destination via thealternate route and to the predefined polyline on one of a shortestroute, a quickest route, and a most efficient route.
 4. A method ofusing a navigation device including a memory and a navigation computer,comprising: a storing in a memory selected map information, the selectedmap information being selected by: providing a predefined polyline thatdefines information, selecting map information that includes a routecorridor as a function of at least one parameter, and if the at leastone parameter provides for the selected map information being tolerantof an error, guiding a driver on one of a side route and an alternateroute, wherein one of: the at least one parameter provides for theselected map information to be tolerant of multiple errors in a startingregion and a destination region of the predefined polyline, and the atleast one parameter provides for the selected map information to betolerant of at least one error as a function of a class of a road; andcausing the navigation computer to generate a navigational instruction.5. The method according to claim 4, wherein the at least one parameterprovides for the selected map information to include a navigationalinstruction.
 6. The method according to claim 5, further comprising:formatting the navigational instruction to lead back to at least one ofa destination via the alternate route and to the predefined polyline onone of a shortest route, a quickest route, and a most efficient route.